Reply by REO

the head stock and tail stock being out of line will not cause an out of round turning. nor when turning with chisels will it cause a tapered turning! when the centers are not tight enough to prevent the center from traveling in the soft grain and causing an oblong slot that the center slides in as it spins or the tail stock bearing center is wearing out the soft grain grabs and the hard grain gets bounced over. These can cause an out of round turning especially when scraping instead of shear cutting. check the end where the tail stock has been supporting it . Is the hole round or oval?